Valve operating mechanism



May 31, 1932. o. N. BRYANT VALVE OPERATING MEcHANIsM 2 Sheets-Sheet l Filed Feb. 28, 1931 O. N. 'Bevan-r.

ATTORNEY` a. w F

ATTORNEY May 31, 1932. o. N. BRYANT VALVE OPERATING uEcHANIsM Filed Feb. 28, 1931 2 sheets-sheet 2 Patented May l31, 17932 Y,

Unirse- STATES PATIENT oi-Fica OZRO-N. BRYANT, OE MOORES, IENNSYLVANIA, ASSIGNOR T WESTINGI'IOUSE ELECTRIC C f & MANUFACTURING C3lWILIWY, A CORPORATION' OF PENNSYLVANIA y VALVE OPERATING MEGHANISM Application led Eebruary 28, 1931. Serial No. 519,085.

My invention relates to. a valve-operating mechanism for a prime mover' having a relatively small and arelatively large admission valve, the motive yfluid admission being provided bythe small valve at the lower rates of admission and being transferred to the large valve when the capacity of the small valve is exceeded.

The object of the invention is to provide mechanism of the vcharacter setforth having improved operation.

A more particularobject is to avoid the frequent transfer of the motive fluid admission from one valve'to the other with relatively small variations in the rate of admissionabove and below a given rate of admission,

In accordance with my invention, provide a mechanism which transfers the admission to the large valve when a predetermined rate of admission is exceeded, but which does not restore admission to the small valve, when it has been transferred toy the large valve, until the rate of admission has decreased below a second predetermined rate of admis.- sion, the latter being a given amount below the irst-mentioned predetermined rate of admission. 1

The above and other objects are effected by my invention as will be apparent from the following description and claims taken in connection with the accompanying drawings, forming a part of this application, in which:

Fig. l is a diagrammatic View showing a prime mover', and the governor and admission valves therefor;

Fig. 2 is a sectional view of the governor; Fig. 3 is a diagrammatic view show-ing the relatively small primary valve, the relatively i0 large secondary valve and the auxiliary control device, each in section; Y

Fig. 3a is a detail sectional view showing another position of the auxiliary control de su the cams for controlling the primary, secondary and tertiary admission valves, respectively; and, 'y

Fig; S is a graphic representation ofV an example of possible variation in the rate oie ad- 13 may be of the same capacity as the primaryvalve.

The primary, secondary and tertiary admission valves communicate with tlie turbine 1() through conduits 111, 15, and 16, respectively, saidconduits conveying the motive fluid to the groups of nozzles shown inFig. L and indicated at. 17, 18 and 19, respectively. It will be noted that the group 18 contains lapproximately twice asv many nozzles as the group 17 ,the capacity of each group being approximately the same as the valve with which it communicates. The nozzles 17 have a ratio of expansion providing the most efieient expansion of steam when the motive fluidfadmission is equal to the capacity ofthe primary valve 11 and the group. of nozzles 17. The nozzles 18liave a lower ratio of expansion, which provides the highest er"- ficiency when the motive fluid admission is equal to the capacity of the secondary valve 12'and the group of nozzles 18.

When the rate of admission is sufficiently low, the motive fluid admission is provided entirely by the primary admission valve 11 and conveyed to the nozzles 17. As the rate of admission exceeds the capacity of said --valve and group of nozzles, the admission through the primary valve is cut oli' and the secondary valve is simultaneously opened to a position providin approximately the same admission. It is, t ereaiter, further opened upon further increase in the rate kof admission. Y

In this arrangement, the nozzles 17 provide best eiciency at light loads. At higher loads at which the ratio of expansionoi these nozzles is too high, an impairment of elliciency is avoided by cutting these nozzles out of service and expanding all the motive fluid in nozzles having a more suitable ratio of expansion.

When the capacity of the secondary valve 12 is exceeded, the tertiary admission valve 13 is opened, in addition to the valve 12, and supplies motive fluid to the group of nozzles 19. The nozzles 19 have an expansion ratio providing highest ciiiciency when the secondary and tertiary valves are in full open position.

The admission valves 11, 12, and 13 are provided with valve actuating mechanisms 21, 22, and 23, respectively. Said mechanisms are controlled by a governor 24, which is responsive to the speed of the turbine 10. The governor 24 is preferably a Huid pressure governor, supplied with fluid pressure varying as the square of the speed by an impeller pump 25 operated by the turbine. Fluid pressure is conveyed from the pump to the governor by a conduit 26.

The governor 24, shown in detail in Fig. 2, includes a casing 30 and an operating piston 27 disposed in a cylinder 28 formed in the casing. The piston is biased upwardly by a compression spring 29, and it is formed with an upper tubular extension 31 anda lower tubular extension 32. The piston and its extensions form a cylinder 33, in which a` pilot valve 34 is disposed. The pilot valve 34 is in the form of a hollow sleeve closed at its upper end. A chamber 37 is formed in the casing 30 below the cylinder 28, and fluid pressure is conveyed to this chamber by the conduit 26. The pressure in this chamber biases the pilot valve 34 and the tubular extension 32 upwardly.

A tension spring 35, which opposes the force of the fluid ypressure on the pilot valve 34, is connected at its upper end to the closed end of the pilot valve, and its lower end is attached to a springholding member 120. The latter has a screw-threaded stem 121 eX- tending through the wall of the chamber 37, and a hand wheel 122 is threaded on the stem. By rotating the hand wheel 122, the spring-holding member 120 may be raised or lowered to change the setting of the governor.

The piston 27 is formed with an annular row of Vports 38 and an annular recess 39, which provide communication between the upper portion of the cylinder 28 and the cylinder 33. An annular row of openings 41 is formed in the tubular extension 32 a short distance below the recess 39 and provides communication betw-een the lower portion of the cylinder 28 and the cylinder An annular row of ports 42 is formed in the kpilot valve and disposed just above the 'recess 39 in the cut-off position of the pilot valve. The latter is also formed with an annular recess 43, the upper edge of which is adjacent the lower edge of the recess 39 in the cut-off position, and which extends downwardly a suicient distance to communicate with the ports 41 when the pilot valve moves above cut-olf position. The lower portion of the cylinder 28 is provided with an outlet 44.

The operation of the governor 24 Vis as follows:

Upon increase in fiuid pressure occasioned by increase in speed of the turbine 10, the pilot valve 34 is moved upwardly against the force of the spring 35. The recess 43 moves into communication with the recess 39, permitting the flow of Huid from the upper portion of the cylinder 28 to the lower portion thereof. Such a. flow is produced by the piston 27, which moves upwardl under the force of the spring 29 and the uid pressure on the lower end of the extension 32, until communication between the recesses 39 and f 43 is again cut off.

Upon decrease in fluid pressure caused by decrease in speed of the turbine 10, the pilot valve 34 is moved downwardly by the spring 35 against the decreased fluid pressure. The ports 42 admit fluid pressure through the recess 39 and the ports 38 to the upper portion of the cylinder 28. The piston 27 is moved downwardly by said fluid pressure until communication between the recess 39 and the ports 42 is again cut off.

The governor controls an auxiliary control device 40, which is preferably mounted on top of the stationary structure of the governor. This deidce controls the transfer of fluid admission between the primary and secondary admission valves, and will be later described in detail.

l The governor 24 controls the valve-actuating mechanisms through a cam shaft 45. Referring to Fig. 2, a lever 4G, fulcrumed on a link 47 is connected at one end to the extension 31 of the operating piston. The other end is connected to the lower end of a. link 48, whose upper end is connected to a crank arm 49 fixed on the cam shaft 45. Upon upward movement of the piston 27, the crank arm 49 is moved downwardly to rock the shaft in clockwise direction as viewed in Fig. f y

2, and upon downward movement of the operating piston 27, the crank arm 49 is moved upwardly to rock the shaft in counterclockwise direction.

The cam shaft 45 extends through the housings of the valve-actuating mechanisms, and carries cam members 51, 52, and 53, disposed within the housings of the actuating mechanisms 21, 22, and 23, respectively.

Referring now to Fig. 3, there are shown f in section the valve-actuating mechanisms 21 and 22 for the primary and secondary valves,

`and the auxiliary control device 40r which controls one or the other of said mechanisms to close the admission valve actuated thereby. I

ln this' figure, these mechanisms have been `taken out of their truerelative positions as show-n vin F ig. 1 and arranged `diagrammatically to illustrate their operative relation. Each valve-actuating mechanism inclu'des an operating piston 54 connected to the associated admission valve. The piston operates in a cylinder 55 and'is biased in valve closing direction by a spring 56. The application of fluid pressure to theoperating piston is controlled by a pilot valve 57 'disposed within a bushing 58 and biased upwardly by a spring 60'.

The bushing 58 is 'formed `with two annular rows of ports 59 and 61, which communicate with ythe upper and lower' portions of the cylinder-'tlirough passages 62 and 63,

respectively.v The bushing is further provided with two annular rows of fluid supply ports 64 and 65 whichcommunicate with any suitable source of fluid pressure,sucli as the pump 25, through a conduit 66 and the conduit 26. An annular row of ports'67 disposed between the ports V59 and 61 provides communication with-a discharge conduitGS. The pilot valve 57 is formed with piston poitions 69 and 71, which cover the ports 59 yand 61, respectively, inthe cut-oilv position of the pilot valve.

A floating lever 72 is connected at one end toa rod 73 xed tothe .piston 54, and at its other'end it is connected to the pilot valve 57 through a link 74. A lever 75, fulcrumed intermediate its ends to a stationary bracket 76, has one endconnected to a link 77, the other end of which 'is connected tothelever 72 intermediate itsends. The other end of the lever 75 carries a roller 78, which engages the surface of the cam member carried on the cam shaft 45, the roller 78 being normally biased against the surface of the cam by the spring 60 Ithrough the connecting levers and links. y p

The operation of each of the rvvalve-actiuiting mechanisms is as follows: The -position of the lever 7 5, which is normally actuated by the cam member, determines the position of the admission valve. Upon clockwise movement of the lever 75, the pilot valve 57 is moved upwardly through the link 7 7 and the lever 7 2. p The pilot valve places the ports 65 and 61 in communication, admitting fluid pressurev from the conduit `66, f

through said portsA and the passage 63 to the lower portion of the cylinder 55'.v The ports 67 and 59 are also placed in communication to provide for the discharge of fluid from the upper portion of the cylinder 55,. through the passage 62 and said ports to the discharge conduitk 68.

The piston 54 moves upwardly and actuates the admission valve in opening direction. The upward movement of the piston also moves the lever 72 in counterclockwise direction' about its connection with the link 77,

Upon counterclockwise movement of the "l lever 75, the pilot valve 57 is moved downwardly, placing the ports 64 and 59 in communication to admit fluid pressure above the piston 54. The ports 61 and 67 are also placed in communication to exhaust fluid from the lower portion of the cylinder 55. The piston moves downwardly in valve-closing direction, andthe pilot valve is moved upwardly through the lever 72 until communicationm through the ports is cut off.

1 80 As thus far described, the several valveactuating mechanisms are the same in conn struction and operation.

Each of the cam members 51, 52, and 53 has an outer circular surface 107 providing closed position of the admission valve, an inner circular surface 108 providing full open position of the admission valve, and an inclined surface 109 for moving the valve between closed and open positions. The position and vform of the inclined surface 109 is'di'flferent for each cam member,and will be referred to later. Y

The valve-actuating mechanism 21 for the primary admission valve is further provided with a piston '79 disposed in a cylinder 81 carried by the housing. rlhe piston 79 cai'- ries a plunger 82, which is adapted to engage an abutment 88 on the left-hand arm of the M lever 75. The piston 79 is biased downwardly by'a spring 84, and fluid pressure may be admitted to the lower portion of the cylinder 81 from a branch of a conduit 85. An orifice 86, which may be formed in the piston 79, provides a restricted discharge of fluid from the lower portion of the cylinder 81.

The valve-actuating mechanism 22 for the secondary admission valve is provided with a piston 87 disposed in a cylinder 88 carried by the housing. T he piston 87 carries a plunger 89 adapted vto engage an abutment 91 carried on the left-hand arm" of the lever 75. The piston 87 is biased upwardly bya spring 92, and fluid pressure may be admitted to the upper portion of the cylinder 88 from a branch of the conduit 85. An orifice 93 is preferably'provided in the branch leading to the cylinder 88. An orifice 94, preferably formed in the pist-on 87, provides a restricted discharge from the upper portion ofthe cyl- Vinder 88.

Then iluid pressure is supplied through the conduit 85 to the cylinders 81 and 88, the piston 87 and the plunger 89 of the mechanism 22 move the lever 75 in counterclockwise direction, eilecting complete closing of the secondary valve 12 independently of the cam member 52. At the same time, the piston 79 of the mechanism 21 raises the plunger 82,

' ly by a spring 106. The upper 311'). mem

permittinor the lever 75 to be controlled by the lier 51.

When the supply of Huid pressure is cut off, the fluid in the cylinders escapes through the orifices 94 and 86. The spring 92 raises the piston 87, permitting the lever 75 of the mechanism 22 to engage the cam member 52. The piston 79 and the plunger 82 of the mechanism 21 are moved by the spring 84 into engagement with the abutment 83 on the lever 75 moving the latter in counterclockwise direction to a position effecting complete closing of the primary admission valve 11.

The auxiliary control device includes a housing providing chambers 95 and 96. Fluid pressure is admitted to the chamber 95 through a branch conduit 26l communicating with the conduit 26. The chamber 96 communicates with the conduit 85.

The auxiliary control device 40 further includes a stem 97 which is secured to and actuated in vertical direction by the tubular eX- tension 31 of the Governor. The stem 97 carries a valve member 98 which controls communication between the chambers 95 and 96. The valve member is formed with a sleeve portion 100 fitting on the stem and with an edge 99 adapted to engage a valve seat 101. The stem 97 is formed with a shoulder 102 adapted to abut the lower side of the sleeve portion 100. A compression spring 103, interposed between the valve member and a collar 104 fixed on the stem, biases the valve member upwardly. The stem also carries a slidable collar 105 which is biased downwardend of the spring 106 bears against a spring holding member 106 carried on the stem. The stem is formed with a second shoulder 117 to limit downward movement of the collar 105 relative to the stem.

It will be noted that the sleeve portion of the valve member 98 is shorter than the portion of the stem between the shoulders 102 and 117. When the valve member engages the shoulder 102, there is a clearance 118 between the upper end of the sleeve portion and the lower surface of the collar 105, as shown in Fig.V 3. lhen the valve 98 engages the lower side of the collar 105, there is an equal clearance between the valve member and the shoulder 102, as shown in Fig. 3a. The stem 97 is in the same position in Figs. 3 and 3a.

The operation of the above-described mechanism, as a whole, is as follows:

The movement of the governor will. be described with reference to the graphic representation in Fig. 8, in which the line 110 indicates the position of the governor providing zero admission; the line 111 indicates a position of the governor callingl for a rate of admission somewhat below the capacity of the primary valve 11; the line 112 indicates the position corresponding to the capacity of the primary valve 11; and the line 113 indicates the point at which the secondary valve has fully opened. The position of the governor indicated by the line 111 is that at which the admission is transferred from the secondary valve to the primary valve in the valve-closing movement of the governor.

Assume first that the governor is in the position providing zero admission, indicated in Fig. 8 at A. The extension 31 of the governor 24 and the stem 97 of the auxiliary control device 40 are at the upper end of their travel. The valve member 98 is in an elevated position admitting fluid pressure to the cylinders 88 and 81. The lever 75 of the secondary valve actuating mechanism 22, therefore, is held in counterclockwise position by the plunger 89, maintaining the secondary valve in closed position. The primary valve-actuating mechanism 21, however, is free to respond to the action of the cam member 51. The primary valve remains closed, however, since the roller 78 is held in elevated vpsition by the surface 107 of the cam mem- Upon vmovement of the governor in valve opening direction, the extension 31 moves downwardly and the cam shaft is rotated in counterclockwise direction. The inclined surface 108 of the cam member 51 permits the roller 78 to be moved downwardly, effecting opening movement of the primary admission valve in the manner already pointed out. Assuming the governor to move in valve-closing direction, before the rate of admission has exceeded the capacity of the primary valve, the extension 31 of the governormoves upwardly and the cam shaft 45 is rotated in clockwise direction. The inclined surface 108 of the cam member 51 raises the roller 78 to a closing movement of the primary admission valve. This movement is indicated in Fig. 8 by the line between the points B and C.

The parts of the auxiliary control device 40 are so constructed that, as the governor moves beyond the point correspondin g to the capacity of the primary valve, indicated by the line 112 in Fig. 8, the edge 99 of the valve member 98 engages the valve seat 101. The supply of fluid under pressure tothe chamber 96 and the conduit 85 is thereby cut ofi'. The springr 106 yields to the downward movement of the collar 106, the collar 105 being held by the valve 98.

The downward movement of the plunger 82 controls the valve actuating mechanism 21 to completely close the primary admission valve. The upward movement of the plunger 89 of the mechanism permits the lever 75 to be moved in clockwise direction by the spring until the roller 78 engages the inclined surface 108 of the cam member 52. The rise or height of the inclined surface 108 in this position of the shaft 45 is such that the secondary valve is brought to a position providing the same rate of admission as provided by the primary valve in full open position. This point of transfer of admission from the primary valve to the secondary valve is indicated at D in Fig. 8. Upon further movement of the governor in valve opening direction,y the inclined surface 108k of the cam member 52 eects further opening of the secondary adiission valve, for example, to the point indicated at E in Fig. 8.

Assume novv that the governor moves in Yvalve-closing direction beyond the point indicated by the line 112 to the point indicated at F. As the governor passes the point at Which motive fluid admission Was previously transferred from the primary to the secondary valve, the pressure dierence across the valve member 9.8, caused by the absence of pressure in the chamber 96, holds the valve member tightly against the seat 101. The decrease in motive fluid admission called for by the movement of the governor from E to F is provided by the secondary admission valve, the form of the inclined surface 108 of the mechanism 22 being such as to provide the same admission 'for any given position of the cam shaft 45 as Would be provided by the inclined surface 108 of the primary valveactuating mechanism 21. Assuming nouv movement of the governor in valve-opening direction to G, the secondary valve is moved in opening direction to provide the required admission. A temporary decrease in the ratev of admission has been effected by the secondary admission valve Without. transferring the admission to the primary valve.

Assume novv that the governor moves in valve-closing direction to the point indicated at H in Fig. 8, which is below the line 111. As the governor passes the point indicated by the line 111, the shoulder 102 of the stem 97 comes into engagement with the loW- er end of the sleeve portion 100. Upon further movement of the stem 97, the valve member is forcibly raised from its seat against the force of the fluid pressure. As soon as the valve is raised lfrom its seat, fluid under pressure is admitted to the chamber 96. A s soon as pressure is obtained in the Chamber 96 to balance thepressure above'the valve member, the spring 108 is eective to raise the valve member 98 until the sleeve portion 100 abuts the collar 105. VIt is held in that position, due to the fact that the spring 106 is stronger than the spring 103. The supply of fluid pressure to the chamber 96 and in the conduit 85 closes the secondary valve and permits the primary valve to be opened. The inclined surface 108 of the mechanism 21 provides the proper valve-opening. The fluid admission is now provided by the primary admission valve,and this con- 'f dition obtains until the governor again moves above the point indicated by the line 112.

From the above description, it Will be seen that Vif the rate of admission varies slightly so as to move the `governor'slightly above and below the point indicated by the line 112, theadmission is continuously carried b f the secondary valve. Likewise, if the acmission varies in the neighborhood of the line 111, the admission is carried by the rprimary admission valve. It isA apparent, therefore, that I avoid a frequent transfer of the motive fluid admission from one valve to the other. f

Vhile I have shown my rinvention in but one form, it Will be obvious to those skilled inthe -art that it is not so limited, but is susceptible of various changes and modifications, Without departing from the spirit thereof, and I desire, therefore, that only such ylimitati-ons shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

lVhat l claim is:

l., The combination With a prime mover having a relatively small and a relatively large admission valve, of mechanism for operating said valves comprising a governor responsive to an operating condition of the 'prime mover, and means for simultaneously placing the large valve under regulation of the governor and closing the small valve upon movement of the governor beyond a given` point in valve-opening direction, and for simultaneously placing the small valve under regulation of the governor and closing the large valve upon movement of the governor in valve-closing direction a predetermined amount beyond said given point. Y

v2. The combination with a prime mover havinga relatively small and a relatively large admission valve, of mechanism for operating said valves comprising `a control member, means responsive to movement vof the control member for actuating the small valve, a second means responsive to move'- ment of the control member for actuating the largevalve, andineans responsive to movement of the control memberbeyond a predetermined point in valve-opening direction for controlling kthe first-mentioned rmeans to close the small valve and permitting the second means to respond to the control member, and responsive to movement of the con'- trol member a predetermined point in valveclosing direction for Vcontrolling the second means to close the large valve and permitting the first-mentioned means to respond to the control member.

3. The combination With a prime mover having relatively small and a relatively large admission valve, of mechanism for operating said valves comprising a governor` n the governor beyond a given point in valveopening direction, and, when thus operated, maintaining the large valve under regulation of the governor and the small valve closed' until the governor has moved in valve-closing direction a predetermined amount beyond said given point, and then closing the large valve and placing the small valve under regulation of the governor. lo 4. The combination with a prime mover having a relatively small and a relatively large admission valve, of mechanism for operating said valves comprising a control means, means controlled by said control u means yfor actuating the small valve, means controlled by said' control means for actuating the large valve, and means which is effective alternatively to cause closing of the small valve While permitting the large valve zo to be opened by its actuating means or to cause closing of the large valve While permitting the small valve to be opened by its actuating means, said means being responsive to operation of the control means in valve- 25 opening direction past a predetermined point to effect the iirst-mentioned condition and maintaining said first-mentioned condition until the control means operates in valve-closing direction past a point which is n a predetermined amount beyond the firstmentioned point in valve-closing direction, and being then effective to maintain the second-mentioned condition until the control means again operates in valve-opening 35v direction beyond the tiret-mentioned point. 5. The combination With a prime mover having a relatively small and a relatively large admission valve, of mechanism for operating said valves comprising a governor 4. responsive to an operating condition of the prime mover, means controlled by said governor for actuating the small valve, means controlled by said governor for actuating the large valve, and means which is I eii'ective alternatively to cause closing of the small valve While permitting the large valve to be opened by its actuating means or to cause closingy of the large valve While permitting the small valve to be opened by its actuating means, said means being responsive to movement of the governor in valve-y opening direction beyond a predetermined point to effect the first-mentioned condition and maintaining said first-mentioned condi- M tion until the governor moves in valve-closing l direction beyond a point which is a predetermined amount beyond the first-men tioned point in valve-closing direction, and y being then effective to maintain the second- 0 mentioned condition until the control means again operates in va'lve-opening direction beyond the first-mentioned point.

In testimony whereof, I have hereunto subscribed my name this 26th day of F eb., 1931. Y f OZRO N. BRYANT. 

